The present invention relates to cutting machines in general, and more particularly to improvements in machines for shredding tobacco or like fibrous materials. Still more particularly, the invention relates to improvements in apparatus for sharpening the cutting edges of orbiting knives on the rotary knife holder in a tobacco shredding or like machine.
Commonly owned U.S. Pat. No. 3,748,786 to Elsner et al. discloses an apparatus for sharpening the orbiting knives in a tobacco shredding machine by means of one or more grinding wheels which have annular grinding surfaces. An advantage of annular grinding surfaces is that their dimensions do not decrease as a result of wear upon the grinding wheel. The orientation of the grinding wheel or wheels in the machine of Elsner et al. is such that the grinding surfaces of such wheels can sharpen only straight cutting edges. However, it is presently preferred to employ shredding knives with undulate cutting edges because this contributes to the ability of shreds to form tobacco fillers which offer a pronounced resistance to deformation. Such types of smokers' articles are preferred by a large majority of smokers as well as by the manufacturers of cigarettes or the like because of savings in tobacco which is the most expensive constituent of each smokers' product. Thus, a given quantity of tobacco shreds which are obtained by severing tobacco leaves or sheets of reconstituted or substitute tobacco with knives having undulate cutting edges can be converted into a cigarette whose resistance to deformation is much higher than that of a cigarette containing the same quantity of shreds which are obtained in a machine employing knives with straight cutting edges.